Field of the Disclosure
The present disclosure relates generally to wireless communication systems and, more particularly, to streaming content to user equipment in wireless communication systems.
Description of the Related Art
Wireless communication systems support streaming services using either broadcast/multicast (MBMS) transmissions to groups of user equipment or dedicated unicast transmission to individual user equipment. Broadcast/multicast services provide the same packets at the same time to all the user equipment that are receiving the broadcast/multicast service. Thus, broadcast/multicast services are most suitable for programs such as live sporting events that are viewed by all users at precisely the same time. However, broadcast/multicast services do not permit users to view the same content at different times, e.g., two users cannot receive the same multicast program from the beginning at different times. Moreover, broadcast/multicast services do not support re-transmission of packets that were not successfully received by one or more user equipment. For example, broadcast/multicast services do not support hybrid automatic repeat request (HARQ) functionality. Radio resources are allocated to the broadcast/multicast services based on a worst-case scenario to ensure that the quality of the broadcast/multicast service is sufficiently high even at locations within the coverage area that have the lowest channel qualities. Broadcast/multicast services therefore tend to be very inefficient.
Unicast services provide a dedicated stream of packets to a single user equipment. Users may therefore start programs or downloads independently of any other users that may be receiving the programs or downloads using a different dedicated stream of packets provided by the unicast service. Unicasting is therefore typically used for streaming services such as pay-per-view streaming of movies or sporting events and downloading large files. Unicasting may be more efficient than broadcasting or multicasting because radio resources are allocated to unicast services based on the channel quality to the receiving user equipment. However, unicasting content may be inefficient and problematic in areas that include a large density of user equipment that are requesting access to the same content. For example, a large number of users in a conference room may want to download the same set of files during the same period of time. For another example, fans in a stadium watching a sporting event may request replays of exciting parts of the game at roughly the same time. In either case, unicasting packets from the same unicast service to a large number of users in the same area may require multiple concurrent streams that can generate congestion, which may lead to reduced quality of user experience, e.g., because of long download times or blocked access to the service.